die Sachebene — the level of the matter.
die Beziehungsebene — the level of the relationship. The pair is used to say where a problem lies: Das Problem liegt auf der Beziehungsebene. The problem is on the level of the relationship. It is also used to bring a meeting back: Bleiben wir auf der Sachebene. Let’s stay on the level of the matter.
nachtragend — carrying something after you, holding a grudge. People say of themselves Ich bin nicht nachtragend, I don’t hold grudges.
Schwamm drüber! — Sponge over it! Let it be wiped away and forgotten.